Apparatus for injecting coolant for fuel cell vehicle

ABSTRACT

An apparatus for injecting a coolant for a fuel cell vehicle is provided. More specifically, a coolant tank stores a coolant and a coolant pump, disposed in a coolant supply line connecting the coolant tank and the stack cooling loop is configured to pressure-transfer the coolant to the stack cooling loop, and circulating the coolant, which has passed through the stack cooling loop, to the coolant tank. A bubble elimination unit, disposed at a rear stage of the coolant pump in the coolant supply line, eliminates the bubbles in the fuel cell stack through vibration. This bubble elimination unit may be configured as an ultrasonic wave excitor for exciting the stack cooling loop with ultrasonic waves.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2010-0125096 filed in the Korean IntellectualProperty Office on Dec. 8, 2010, the entire contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a refrigerating system of a fuel cellvehicle and, more particularly, to an apparatus for injecting coolantinto a stack cooling loop, and a water/heat management system of a fuelcell vehicle.

(b) Description of the Related Art

A fuel cell vehicle including a fuel cell system produces electricity bysupplying hydrogen used as fuel to a fuel cell stack, and operates anelectric motor with the electricity produced via the fuel cell stack todrive a vehicle. Thus, a fuel cell system is a sort of a powergeneration system for directly electrochemically converting chemicalenergy of fuel (hydrogen) into electric energy within a fuel cell stack,rather than changing the chemical energy into heat through combustion.

The fuel cell stack is formed by stacking tens to hundreds of unit fuelcells together. Each fuel cell is generally comprised of a membraneelectrode assembly (MEA), a gasket, a separator, and the like, to obtaina desired output. Fuel cell stacks generate a large quantity of heatalong with a fuel cell reaction, so the fuel cell system requires acooling system for cooling the stack.

The cooling system for a fuel cell vehicle typically uses antifreeze asa coolant via a coolant injection process is often performed during themanufacture of a vehicle. In general, in order to inject the coolant, amethod of vacuumizing an overall coolant line and injecting apressurized coolant is employed. The reason for vacuumizing the entirecoolant line is to prevent the presence of bubbles in the interior ofthe cooling system. If bubbles (air) exist in the interior of thecooling system, the coolant overflows when the vehicle is driven,causing a shortage of the coolant as a result, thus, increasing thepossibility of overheating.

In particular, when bubbles exist in the interior of a fuel cell stackof the fuel cell vehicle, stack efficiency and cooling performance aredegraded due to an increase in a local temperature, and the fuel cellmay be damaged as a result. Thus, elimination of the bubbles ininjecting the coolant is requisite.

However, in the vehicle fuel cell system, a stack is fabricated bystacking hundreds to thousands of sheets of components, and gaskets areused for air-tightness, so when it is exposed to the vacuum state, theair tightness can be hard to maintain, and in a worst-case scenario, theseparator may be damaged. Thus, in fuel cell vehicles, the use of acoolant injection apparatus for an engine vehicle requires extremecaution.

Accordingly, in an effort to improve this, a press circulation typecoolant injection apparatus for circulatively charging a coolant to theinterior of a flow path of a cooling system by using a coolantcirculating apparatus has been proposed. In this case, however, it isnot easy to eliminate bubbles from the interior of the stack. In orderto eliminate bubbles from the interior of the stack, the coolant must becirculated at a very high speed, resulting in an excessive increase inthe pressure in the cooling system which negatively affects theair-tightness of the stack and may damage components such as theseparator, or the like.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention andtherefore it may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY OF THE INVENTION

The present invention provides an apparatus for injecting a coolant fora fuel cell vehicle which eliminates bubbles from the interior of a fuelcell stack in injecting a coolant to a stack coolant loop.

An exemplary embodiment of the present invention provides an apparatusfor injecting a coolant to a stack cooling loop for cooling a fuel cellstack in a fuel cell vehicle. The apparatus includes a coolant tankconfigured to store a coolant; a coolant pump formed in a coolant supplyline connecting the coolant tank and the stack cooling loop topressure-transfer the coolant to the stack cooling loop, and circulatingthe coolant, which has passed through the stack cooling loop, to thecoolant tank; and a bubble elimination unit disposed at a rear stage ofthe coolant pump in the coolant supply line and configured to eliminatebubbles in the fuel cell stack through vibration, wherein the bubbleelimination unit is configured as an ultrasonic wave excitor forexciting the stack cooling loop with ultrasonic waves.

In the apparatus for injecting a coolant for a fuel cell vehicle, theultraviolet excitor may be configured as a piezoelectric element or in amagnetic manner and the stack cooling loop and the coolant tank may beconnected through a first coolant circulation line. Additionally, thefirst coolant circulation line may supply bubbles, which are eliminatedfrom the fuel cell stack, to the coolant tank.

In the exemplary apparatus for injecting a coolant for a fuel cellvehicle, the coolant tank may include a first outlet connected to thecoolant supply line, a first inlet connected to the first coolantcirculation line, and a bubble outlet for allowing the bubbles to beexhausted therethrough to the outside. A filter unit may be installed atthe rear stage of the coolant pump in the coolant supply line and asecond outlet and a second inlet may be formed at the cooling tank. Thesecond outlet and the second inlet may be interconnected through asecond coolant circulation line.

In the apparatus for injecting a coolant for a fuel cell vehicle, afilter pump and a filter unit may be installed in the second coolantcirculation line. The filter unit may be configured as an ion eliminatorcharged with an ion exchange resin.

According to an exemplary embodiment of the present invention, when thecoolant is injected into the stack cooling loop, bubbles within the fuelcell stack can be easily eliminated through the ultraviolet excitor.Thus, in the present exemplary embodiment, the elimination of thebubbles present in the interior of the stack prevent an increase in alocal temperature of the stack otherwise caused by bubbles or air in theline, thus improving operation efficiency and cooling performance of thestack, and preventing damage to the fuel cell otherwise caused by anincrease in the local temperature.

In addition, in the present exemplary embodiment, unlike the related artin which bubbles are eliminated from the interior of the stack byinjecting the coolant with an excessive amount of pressure, bubbles areeliminated through a simple excitation via ultraviolet waves withoutapplying pressure to the coolant, and thus, the air-tightness of thestack cannot be broken otherwise by the excessive pressure of thecoolant and the components can be prevented from being damaged.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawings,which are given by illustration only, and thus are not limiting to thepresent invention.

FIG. 1 is a schematic block diagram of an apparatus for injecting acoolant for a fuel cell vehicle according to an exemplary embodiment ofthe present invention.

FIG. 2 is a schematic block diagram of an apparatus for injecting acoolant for a fuel cell vehicle according to another exemplaryembodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present invention will be described more fully hereinafter withreference to the accompanying drawings, in which exemplary embodimentsof the invention are shown. As those skilled in the art would realize,the described embodiments may be modified in various different ways, allwithout departing from the spirit or scope of the present invention.

In order to clarify the present invention, parts that are not connectedwith the description will be omitted, and the same elements orequivalents are referred to as the same reference numerals throughoutthe specification.

The size and thickness of each element are arbitrarily shown in thedrawings, and the present invention is not necessarily limited thereto,and in the drawings, the thickness of layers, films, panels, regions,etc., are exaggerated for clarity.

It is understood that the term “vehicle” or “vehicular” or other similarterm as used herein is inclusive of motor vehicles in general such aspassenger automobiles including sports utility vehicles (SUV), buses,trucks, various commercial vehicles, watercraft including a variety ofboats and ships, aircraft, and the like, and includes hybrid vehicles,electric vehicles, plug-in hybrid electric vehicles, hydrogen-poweredvehicles and other alternative fuel vehicles (e.g., fuels derived fromresources other than petroleum). As referred to herein, a hybrid vehicleis a vehicle that has two or more sources of power, for example bothgasoline-powered and electric-powered vehicles.

FIG. 1 is a schematic block diagram of an apparatus for injecting acoolant for a fuel cell vehicle according to an exemplary embodiment ofthe present invention.

With reference to FIG. 1, an apparatus 100 for injecting a coolant for afuel cell vehicle according to an exemplary embodiment of the presentinvention serves to inject a coolant into a stack cooling loop 1, asystem for cooling a fuel cell stack as a power generation module of afuel cell vehicle. Here, the stack cooling loop 1 is provided as athermal/water management system (TMS) which removes heat generated fromthe fuel cell stack, controls an operation temperature of the stack, andperforms one or more water management functions. The thermal/watermanagement system, includes a radiator, a cooling fan, a heater, acontroller, a water pump, or the like, is widely known in the art, so adetailed description of a configuration thereof will be omitted.

Meanwhile, the foregoing fuel cell stack is configured as an electricalgeneration aggregate in which unit fuel cells generating electricalenergy according to an electrochemical reaction between fuel and anoxidizing agent are continuously arranged. In this case, heat isgenerated when the fuel cell stack generates electrical energy, so acoolant passage allowing the coolant to be circulated therealong isconfigured between the unit fuel cells as mentioned above.

The apparatus 100 for injecting a coolant for a fuel cell vehicleaccording to the present exemplary embodiment has a structure in whichbubbles in the interior of the fuel cell stack are easily eliminatedwhen the coolant is injected into the stack cooling loop 1. To this end,the apparatus 100 for injecting a coolant for a fuel cell vehicleaccording to the present exemplary embodiment includes a coolant tank10, a coolant pump 40, and a bubble elimination unit 80. These elementswill now be described.

In the present exemplary embodiment, the coolant tank 10 may be a watertank storing the coolant, which is configured to supply the coolant tothe stack cooling loop 1 and allow the coolant, which has passed throughthe stack cooling loop 1, to flow thereinto. To this end, the coolanttank 10 includes a first outlet 11 allowing the coolant to be exhausttherethrough, and a first inlet 13 allowing the coolant, which haspassed through the stack cooling loop 1, to be introduced therethrough.

The first outlet 11, serves to allow the coolant to be exhaustedtherethrough to the fuel cell stack, e.g., the stack cooling loop 1, maybe connected back to the stack cooling loop 1 through a coolant supplyline 21. On the other hand, the first inlet 13, which serves to allowthe coolant, which has passed through the stack cooling loop 1, to bere-circulated to the coolant tank 10, to be connected to the stackcooling loop 1 through a first coolant circulation line 23.

Meanwhile, a bubble outlet 17, allowing bubbles to be exhaustedtherethrough from the interior of the fuel cell stack which has beeneliminated by the bubble elimination unit 80 (to be described), isformed at the coolant tank 10, and in this case, the bubble outlet 17may be formed on an upper/top end portion of the coolant tank 10.

In the present exemplary embodiment, the coolant pump 40pressure-transfers the coolant stored in the coolant tank 10 to thestack cooling loop 1 through the coolant supply line 21. The coolantpump 40 serves to forcibly circulate the coolant, which has passedthrough the stack cooling loop 1, to the coolant tank 10 through thefirst coolant circulation line 23. The coolant pump 40 is installed inthe coolant supply line 21, and since it is configured as a known waterpump commonly employed in a cooling system in the art, a detaileddescription thereof will be omitted.

The filter unit 60 may be configured at a rear stage of the coolant pump40 in the coolant supply line 21. The filter unit 60 is configured as anion eliminator charged with a ion exchange resin. Before the coolant issupplied to the stack cooling loop 1, the filter unit 60 eliminatesmetal ions from the coolant so that the coolant has an electricconductivity higher than the level required for the fuel cell vehicle.The bubble elimination unit 80 then eliminates bubbles from the interiorof the fuel cell stack through vibration when the coolant is injectedinto the stack cooling loop 1. The bubble elimination unit 80 may beconfigured as an ultrasonic wave excitor 81 for exciting the stackcooling loop 1 with ultrasonic waves by using the coolant supplied tothe fuel cell stack of the stack cooling loop 1. The ultrasonic waveexcitor 81 may be formed at a rear stage/subsequent to the filter unit60 in the coolant supply line 21.

When the coolant is injected into the stack cooling loop 1, theultrasonic wave excitor 81 generates ultrasonic waves to oscillate thecoolant with the ultrasonic waves to excite the coolant passage in thefuel cell stack, thus eliminating the bubbles in the interior of thefuel cell stack. The ultrasonic wave excitor 81 is configured in amagnetic manner or piezoelectric element manner widely known in the art,so a detailed description thereof will be omitted.

Here, the bubbles eliminated from the coolant passage of the fuel cellstack according to the excitation by the ultrasonic waves are suppliedalong with the coolant to the coolant tank 10 through the first coolantcirculation line 23 as mentioned above. Namely, the bubbles eliminatedfrom the coolant passage of the fuel cell stack are supplied to thecoolant tank 10 along with the coolant through the first coolantcirculation line 23 by the coolant pump 40, and air generated from theeliminated bubbles can be discharged to the outside through the bubbleoutlet 17 of the coolant tank 10.

In FIG. 1, reference numeral 90 denotes a supply valve formed betweenthe filter unit 60 and the ultrasonic wave excitor 81 in the coolantsupply line 21 in order to selectively prevent a supply of the coolantfrom being injected into the stack cooling loop 1.

Thus, in the apparatus 100 for injecting a coolant for a fuel cellvehicle according to an exemplary embodiment of the present inventionconfigured as described above, the coolant of the coolant tank 10 isexhausted through the first outlet 11 by operating the coolant pump 40.The coolant passes through the filter unit 60 of the coolant supply line21, and in this case, in the present exemplary embodiment, metal ions ofthe coolant are removed by the ion exchange resin of the filter unit 60,whereby the electrical conductivity of the coolant can be maintained ata level higher than what is required for the fuel cell vehicle. Throughthe foregoing process, the coolant is injected into the stack coolingloop 1, and in this process, the ultrasonic wave excitor 81 according tothe present exemplary embodiment generates ultrasonic waves andoscillates the coolant with the ultrasonic waves to thus eliminatebubbles in the interior of the fuel cell stack.

Meanwhile, in the present exemplary embodiment, the coolant, which haspassed through the stack cooling loop 1, is circulated to the coolanttank 10 along (or through) the first coolant circulation line 23 througha pumping operation performed by the coolant pump 40. In this process,as mentioned above, the bubbles, which have been removed from theinterior of the fuel cell stack by the ultrasonic wave excitor 81, aresupplied along with the coolant to the coolant tank 10 through the firstcoolant circulation line 23. And then, air generated from the bubbles isexhausted from the interior of the coolant tank 10 to the outsidethrough the bubble outlet 17.

As described above, in the apparatus 100 for injecting a coolant for afuel cell vehicle according to the present exemplary embodiment of thepresent invention, when the coolant is injected into the stack coolingloop 1, bubbles in the interior of the fuel cell stack can be easilyeliminated by the ultrasonic wave excitor 81. Thus, in the presentexemplary embodiment, since the bubbles present in the interior of thestack are eliminated, an increase in the local temperature of the stackotherwise created by the bubbles can be prevented, thus enhancing theoperation efficiency and cooling performance of the stack, andpreventing damage to the fuel cell caused otherwise due to the increasein the local temperature.

In addition, in the present exemplary embodiment, unlike the related artin which bubbles are eliminated from the interior of the stack byinjecting the coolant with an excessive pressure, bubbles are eliminatedthrough simple excitation by ultraviolet waves without applying pressureto the coolant, and thus, the air-tightness of the stack cannot bebroken otherwise by the excessive pressure of the coolant and thecomponents can be prevented from being damaged.

FIG. 2 is a schematic block diagram of an apparatus for injecting acoolant for a fuel cell vehicle according to another exemplaryembodiment of the present invention.

With reference to FIG. 2, unlike the apparatus 100 for injecting acoolant for a fuel cell vehicle according to the previous exemplaryembodiment in FIG. 1, in an apparatus 200 for injecting a coolant for afuel cell vehicle according to another exemplary embodiment of thepresent invention, the filter unit 160 is not mounted in the coolantsupply line 121, and a coolant circulation path is configured at acoolant tank 110 and the filter 160 is disposed within the coolantcirculation path.

To this end, in the present exemplary embodiment, a first outlet 111, afirst inlet 113, an air outlet 117, a second outlet 112, and a secondinlet 114 are formed at the coolant tank 110. Here, the second outlet112 and the second inlet 114 are connected through the second coolantcirculation line 124 and the foregoing filter unit 160 is installed inthe second coolant circulation line 124. In this case, a filter pump 126is installed at a front stage of the filter unit 160 in the secondcoolant circulation line 124. The filter pump 126 pressure-transfers acoolant stored in the coolant tank 110 to the filter unit 160 to allowthe coolant to be circulated to the coolant tank 110 through the secondcoolant circulation line 124.

Accordingly, the coolant stored in the coolant tank 110 is exhaustedthrough the second outlet 112 of the coolant tank 110 through thepumping operation performed by the filter pump 126, flows along thesecond coolant circulation line 124, and is circulated to the interiorof the coolant tank 110 through the second inlet 114. In this process,the coolant passes through the filter unit 160 in which metal ions ofthe coolant are removed by the ion exchange resin, and the metalion-free coolant is recirculated to the coolant tank 110.

Other configurations of the apparatus 200 for injecting a coolant for afuel cell vehicle according to the present exemplary embodiment, namely,a configuration of an ultrasonic wave excitor 181 of a bubbleelimination unit 180, a structure for injecting the coolant to the stackcooling loop 1, a coolant circulation structure through a coolant pump140 and a first coolant circulation line 123, and the like, are the sameas those of the former exemplary embodiment, so a detailed descriptionthereof will be omitted.

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

DESCRIPTION OF SYMBOLS

-   -   1 . . . stack cooling loop    -   10, 110 . . . coolant tank    -   11, 111 . . . first outlet    -   13, 113 . . . first inlet    -   17 . . . bubble outlet    -   21, 121 . . . coolant supply line    -   23 . . . first coolant circulation line    -   40 . . . coolant pump    -   60, 160 . . . filter unit    -   80 . . . bubble elimination unit    -   81 . . . ultrasonic wave excitor    -   112 . . . second outlet    -   114 . . . second inlet    -   124 . . . second coolant circulation line    -   126 . . . filter pump

1. An apparatus for injecting a coolant into a stack cooling loop forcooling a fuel cell stack in a fuel cell vehicle, the apparatuscomprising: a coolant tank storing a coolant; a coolant pump formed in acoolant supply line configured to connect the coolant tank and the stackcooling loop to pressure-transfer the coolant to the stack cooling loop,and circulate the coolant, which has passed through the stack coolingloop, to the coolant tank; and a bubble elimination unit disposed at arear stage of the coolant pump in the coolant supply line, the bubbleelimination unit configured to eliminate bubbles in the fuel cell stackthrough vibration, wherein the bubble elimination unit is configured asan ultrasonic wave excitor for exciting the stack cooling loop withultrasonic waves.
 2. The apparatus of claim 1, wherein the ultravioletexcitor is configured as a piezoelectric element or in a magneticmanner.
 3. The apparatus of claim 1, wherein the stack cooling loop andthe coolant tank are connected through a first coolant circulation line,and the first coolant circulation line supplies bubbles, which areeliminated from the fuel cell stack, to the coolant tank.
 4. Theapparatus of claim 3, wherein the coolant tank comprises a first outletconnected to the coolant supply line, a first inlet connected to thefirst coolant circulation line, and a bubble outlet for allowing thebubbles to be exhausted therethrough to the outside.
 5. The apparatus ofclaim 1, wherein a filter unit is installed at the rear stage of thecoolant pump in the coolant supply line.
 6. The apparatus of claim 5,wherein the filter unit is configured as an ion eliminator charged withan ion exchange resin.
 7. The apparatus of claim 1, wherein a secondoutlet and a second inlet are formed at the cooling tank, the secondoutlet and the second inlet interconnected through a second coolantcirculation line, and a filter pump and a filter unit installed withinthe second coolant circulation line.
 8. The apparatus of claim 7,wherein the filter unit is configured as an ion eliminator charged withan ion exchange resin.
 9. A method for injecting a coolant into a stackcooling loop for cooling a fuel cell stack in a fuel cell vehicle, theapparatus comprising: storing a coolant in a tank pressure-transferring,by a first pump through a coolant supply line, the coolant to the stackcooling loop, and circulating the coolant by connecting the coolant tankand the stack cooling loop, the coolant having already passed throughthe stack cooling loop, to the coolant tank, wherein the coolant pump isformed in the coolant supply line; eliminating bubbles in the fuel cellstack through vibration by a bubble elimination unit disposed at a rearstage of the coolant pump in the coolant supply line, wherein the bubbleelimination unit is configured as an ultrasonic wave excitor forexciting the stack cooling loop with ultrasonic waves.
 10. The method ofclaim 9, wherein the ultraviolet excitor is configured as apiezoelectric element or in a magnetic manner.
 11. The method of claim9, further comprising supplying bubbles through a first coolantcirculation line which are eliminated from the fuel cell stack, to thecoolant tank wherein the stack cooling loop and the coolant tank areconnected through the first coolant circulation line.
 12. The method ofclaim 11, wherein the coolant tank includes a first outlet connected tothe coolant supply line, a first inlet connected to the first coolantcirculation line, and a bubble outlet for allowing the bubbles to beexhausted therethrough to the outside.
 13. The method of claim 9,wherein a filter unit is installed at the rear stage of the coolant pumpin the coolant supply line.
 14. The method of claim 13, wherein thefilter unit is configured as an ion eliminator charged with an ionexchange resin.
 15. The method of claim 9, wherein a second outlet and asecond inlet are formed at the cooling tank, the second outlet and thesecond inlet interconnected through a second coolant circulation line,and a filter pump and a filter unit installed within the second coolantcirculation line.
 16. The apparatus of claim 15, wherein the filter unitis configured as an ion eliminator charged with an ion exchange resin.